The uncontrolled dendrite growth and shuttle effect of polysulfides have hindered the practical application of lithium–sulfur (Li–S) batteries. Herein, a metal–organic framework-derived Ag/C core–shell composite integrated with a carbon nanofiber film (Ag/C@CNF) is developed to address these issues in Li-S batteries. The Ag/C core–shell structure design endows the CNF skeleton with enhanced electrical conductivity, electrocatalysis performance toward polysulfides conversion, and lithium nucleation. When served as a freestanding bifunctional host in Li-S batteries, the Ag/C@CNF composite regulates the Li and sulfur electrochemical processes by guiding the uniform Li deposition with mitigated dendrite growth and at the same time accelerating the polysulfides conversion. The assembled Li–S full battery delivers a considerable capacity of 650 mAh g-1, an ultralong cyclability with an attenuation rate as low as 0.02% per cycle for 1000 cycles at 5 C, and excellent rate performances at increased sulfur loading up to 7.6 mg cm-2 under lean electrolyte condition.